Wound care device having fluid transfer and adhesive properties

ABSTRACT

This disclosure relates to a wound care device which contains capillary force one-way pumps that are capable of transporting fluid, such as wound exudate, away from a wound site to the opposite side of the wound care device, which functions as a segregated fluid reservoir. This fluid transport mechanism generally aids in reducing wound maceration by removing excess wound fluid and the protease enzymes and infectious bacteria contained within the wound fluid. The wound care device performs this function, often times for multiple days, without the loss of the physical integrity of the wound care device. In addition to providing a uni-directional fluid transport mechanism, the wound care device contains a perforated adhesive layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a divisional of U.S.application Ser. No. 16/415,073, entitled “Wound Care Device HavingFluid Transfer and Adhesive Properties” which was filed on May 17, 2019,which claims priority to U.S. Provisional Patent Application No.62/674,095, entitled “Wound Care Device Having Fluid Transfer andAdhesive Properties” which was filed on May 21, 2018, both of which areentirely incorporated by reference herein.

TECHNICAL FIELD

This disclosure relates to a wound care device which contains capillaryforce one-way pumps that are capable of transporting fluid, such aswound exudate, away from a wound site to the opposite side of the woundcare device, which functions as a segregated fluid reservoir. This fluidtransport mechanism generally aids in reducing wound maceration byremoving excess wound fluid and the protease enzymes and infectiousbacteria contained within the wound fluid. The wound care deviceperforms this function, often times for multiple days, without the lossof the physical integrity of the wound care device. In addition toproviding a uni-directional fluid transport mechanism, the wound caredevice contains a perforated adhesive layer.

In one aspect, the wound care device is comprised of a knit constructioncharacterized in that polyester fiber is primarily present on the woundcontact surface and nylon fiber is primarily present on the fluidreservoir surface. A third fiber, such as an elastomeric polyurethaneknown by the tradename Lycra®, may also be included in order to providesome amount of elasticity to the wound care device. The wound caredevice provides a one way directional flow of fluid away from the woundand into the nylon fluid reservoir. The perforated silicone gel adhesivelayer, which is designed for direct contact with the wound, functions toprevent the wound care device from sticking to the wound.

BACKGROUND

In the medical field, and in the area of wound care particularly, it iswell-established that many factors, including the amount of moisturepresent at a wound site, affects how quickly a wound will heal.Generally speaking, having an excessive amount of moisture present at awound site, especially when combined with the warm environment providedby the body, leads to undesirable bacteria growth and production ofprotease enzymes in the wound. Such growth can cause further damage tohealthy cells and delay the healing process. However, insufficientmoisture at the wound site can cause eschar (scab) formation andscarring and may cause the wound care device, or medical dressing, toadhere to the wound. If the dressing adheres to the wound, subsequentremoval of the dressing may cause undue discomfort to the patient aswell as disrupt newly granulated tissue. Infection of the wound may alsobe compounded when a medical dressing is removed and portions of thedressing remain behind in the wound itself, particularly if the dressingis already colonized with pathogenic microbes. Thus, it is importantthat the dressing maintains its physical integrity when exposed tostress, such as during removal from the wound, in order to preventadditional complications and delays in healing.

Absorptive materials such as gauzes, hydrogels, swellable fibers, foams,woven textiles and the like have been incorporated into wound caredevices for the purpose of controlling the wound moisture content.Fluids are generally absorbed by these types of materials by reversiblecapillary action or osmosis rather than by a one-way directional flowcreated by an inventive two-sided wound care device.

For example, U.S. Pat. No. 5,009,652 to Morgan et al. discloses adisposable laminated medical sponge that contains a thin film which isimpervious to fluids and infectious agents. The medical sponge isdesigned to prevent the seepage of bodily fluids from one side of thesponge to the opposite side, since such seepage provides risk ofinfection for health-care workers having direct contact with patients.

U.S. Pat. No. 6,194,332 to Rock et al. discloses an antimicrobialcomposite fabric having a first inner fabric layer and a second outerfabric layer. The inner fabric layer may be comprised of polyester,acrylic or nylon fiber which has been rendered hydrophilic, such as bymechanical or chemical treatment. The hydrophilic inner fabric layerenables the transport of sweat from the inner fabric layer to the outerfabric layer. The fibers in the outer layer of the fabric may be blendedwith antimicrobial fibers in order to reduce the proliferation ofbacteria in this layer. The fabric may be formed into a garment whichprovides reduced body odor. U.S. Pat. No. 6,602,811 to Rock et al.discloses a similar antimicrobial composite fabric, except that thesecond outer fabric layer also may be treated with an antimicrobialpaste.

US Patent Application Publication No. 2004/0001880 to Bowler et al.discloses the use of gel forming fibers such as sodiumcarboxymethycellulose which can be incorporated into wound dressings.Silver ions may be incorporated into the fibers by combining them in asolution with a solvent prior to fiber formation. The dressing may beused as part of a larger dressing or a layer in a multi-layered dressingand need not be in direct contact with the wound.

The wound care device of the present invention takes advantage of aunique textile fabric construction which effectively isolates fluid awayfrom the wound, along with a silicone gel adhesive layer which aids inpreventing the wound care device from detrimentally sticking to thewound. Both of these features promote and improve the healing process.The differentiation that exists in a wound care device having ahydrophobic fiber on the wound contact side of the device andhydrophilic fiber on the fluid reservoir side of the device creates aunique one-way, directional flow of fluid and contaminants away from thewound.

A further feature of the wound care device of the present invention isthat the device may also contain a topical coating of an antimicrobialagent such as silver. It is known that placing surface-available silverin contact with a wound allows the silver to enter the wound and becomeabsorbed by undesirable bacteria and fungi that grow and prosper in thewarm, moist environment of the wound site. Once absorbed, the silverions kill microbes, resulting in treatment of infected wounds or theprevention of infection in at-risk wounds. Methods of topically applyinga silver-based antimicrobial finish to textile substrates are described,for example, in commonly assigned U.S. Pat. Nos. 6,584,668; 6,821,936;and 6,946,433 and in commonly assigned U.S. patent application Ser. Nos.09/586,081; 09/589,179; 10/307,027; and 10/306,968. All of these patentsand patent applications are hereby incorporated by reference. Details ofmany of these processes will be discussed below.

The present disclosure addresses and overcomes the problems describedabove. Whereas, historically, a gauze or foam medical dressing has beenapplied to a wound with at least some intent on absorbing fluids, thepresent disclosure describes a wound care device capable of creating aone-way, directional flow of fluid and contaminants away from the wound,without detrimentally causing excessive dryness of the wound andsubstantial adherence of the device to the wound. The wound care devicemay additionally provide desired release of silver to the wound site forantimicrobial efficacy and, because of its unique construction,maintains its physical integrity when exposed to stress during ordinaryuse of the wound care device.

For these reasons and others that will be described herein, the presentwound care device having unique fluid management properties and easyrelease/removal from the wound represents a useful advance over theprior art.

BRIEF SUMMARY

In one aspect, the invention relates to a wound care device comprising:a perforated trilaminate silicone adhesive layer; a single layer offabric having a wound contact surface and a wound fluid reservoirsurface; a fluid retentive layer; and wherein said wound care devicetransports wound fluid uni-directionally from said wound contact surfaceto said wound fluid reservoir surface upon exposure to a wound.

In another aspect, the invention relates to a wound care devicecomprising: (a) a perforated trilaminate silicone adhesive layer; (b) asingle layer of fabric having a wound contact surface and a wound fluidreservoir surface; (c) optionally, a first hot melt adhesive layer; (d)a fluid retentive layer; (e) optionally, a second hot melt adhesivelayer; (f) optionally, an occlusive film layer; and wherein said woundcare device transports wound fluid uni-directionally from said woundcontact surface to said wound fluid reservoir surface upon exposure to awound.

In a further aspect, the invention relates to a method for managingmoisture at a wound site comprising the steps of: (a) providing a woundcare device comprising: (i) a perforated trilaminate silicone adhesivelayer; (ii) a single layer of fabric having a wound contact surface anda wound fluid reservoir surface; and (iii) a fluid retentive layer; andwherein said wound care device transports wound fluid uni-directionallyfrom said wound contact surface to said wound fluid reservoir surfaceupon exposure to a wound; (b) placing said wound contact surface of saidwound care device in contact with said wound site; and (c) allowing saidwound care device to transport wound fluid uni-directionally from saidwound contact surface to said wound fluid reservoir surface.

In another aspect, the invention relates to a wound care devicecomprising: (a) a perforated trilaminate silicone adhesive layer; (b) asingle layer of fabric having a wound facing surface and a wound fluidreservoir surface; and (c) a fluid retentive layer; and wherein saidwound care device transports wound fluid uni-directionally from saidwound facing surface to said wound fluid reservoir surface upon exposureto a wound.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a wound care device according to theinvention having a fluid transport layer and an apertured adhesivelayer.

FIG. 1B is an exploded perspective view of the wound care devicedepicted in FIG. 1A.

FIG. 1C is a perspective view of a wound care device according to theinvention having a fluid transport layer and an alternative aperturedadhesive layer.

FIG. 1D is a perspective view of a wound care device according to theinvention having a fluid transport layer and a border adhesive layer.

FIG. 1E is a perspective view of another embodiment of a wound caredevice according to the invention having a fluid transport layer and aborder adhesive layer and further illustrating the adhesive layerextending beyond the other layers of the device.

FIG. 2 is a plan view of a laid-in fabric suitable for use as the fluidtransport layer of a wound care device according to the invention.

FIG. 3A is a plan view of an apertured polymeric film, such as thatdepicted in FIGS. 1A and 1B, suitable for use as the adhesive layer of awound care device according to the invention.

FIG. 3B is a side view of a trilaminate apertured polymeric filmsuitable for use as the adhesive layer of a wound care device accordingto the invention.

FIG. 4 is a plan view of a composite article according to the inventionshowing the surface of the composite article having the adhesive layerand the underlying fluid transport layer.

FIG. 5 is a photomicrograph at 20× magnification illustrating multipleapertures in the adhesive layer of the wound care device and thepresence of fibers from the fluid transport layer being present in thoseapertures according to the invention.

FIG. 6 is a photomicrograph at 40× magnification illustrating multipleapertures in the adhesive layer of the wound care device and thepresence of fibers from the fluid transport layer being present in thoseapertures according to the invention.

FIG. 7 is a photomicrograph at 80× magnification illustrating a singleaperture in the adhesive layer of the wound care device and the presenceof fibers from the fluid transport layer being present in the apertureaccording to the invention.

FIG. 8 is a photomicrograph at 2500× magnification illustrating thepresence of silver-containing compounds on the fibers of the fluidtransport layer according to the invention.

FIG. 9 is a photomicrograph at 90× magnification of a side view of aportion of the wound care device according to the invention.

FIG. 10 is a photomicrograph at 100× magnification illustrating theapertures in the adhesive layer of Comparative Example 1.

FIG. 11 is a photomicrograph at 250× magnification illustrating theapertures in the adhesive layer of Comparative Example 1.

FIG. 12 is a photomicrograph at 50× magnification illustrating theapertures in the adhesive layer of Comparative Example 3.

FIG. 13 is a photomicrograph at 100× magnification illustrating a singleaperture in the adhesive layer of Comparative Example 3.

FIG. 14 is a bar graph illustrating antimicrobial efficacy of wound caredevices of the present invention and Comparative Example 1.

DETAILED DESCRIPTION Definitions and Terms

“Hydrophilic” is defined as having a strong affinity for or the abilityto absorb water.

“Hydrophobic” is defined as lacking affinity for or the ability toabsorb water.

“Non-electrically conductive” is defined as having a resistance in ohmsper square inch of fabric of greater than about 10,000 ohms, preferablygreater than about 100,000 ohms and most preferably greater than about1×10⁹ ohms, when measured in accordance with AATCC Test Method 76-1978.

As utilized herein, the term “surface energy” refers to the excessenergy at the surface of a material compared to the bulk of the material(e.g., the interior portions of the material) and is usually expressedin terms of milliJoules per square meter (mJ/m²). The surface energyquantifies the disruption of intermolecular bonds that occurs when asurface is created. The surface energy can be measured by several meansincluding, for example, the Fowkes method. In this method, two referenceliquids are used to first measure the dispersive component and the polarcomponent of the material's surface energy. The surface energy of thematerial is then calculated from the measured dispersive and polarcomponents. In general, a surface having a higher surface energy willexhibit a higher affinity for aqueous fluids, such as perspiration orwound exudate.

Wound Care Device

The wound care device of the present invention is generally intended tobe used for treatment of various wounds including, without limitation,partial thickness burns, incisions, skin grafts, donor sites,lacerations, abrasions, Stage I-IV pressure ulcers, vascular venousstasis, and diabetic ulcers. The wound care device is generallycomprised of: (a) a layer of fabric formed from synthetic fibers,natural fibers, or combinations thereof, and (b) a layer of perforatedsilicone gel adhesive.

Synthetic fibers comprising the fabric layer include, for example,polyester, acrylic, polyamide, polyolefin, polyaramid, polyurethane,regenerated cellulose (i.e., rayon), and blends thereof. The term“polyamide” is intended to describe any long-chain polymer havingrecurring amide groups (—NH—CO—) as an integral part of the polymerchain. Examples of polyamides include nylon 6; nylon 6, 6; nylon 1, 1;and nylon 6, 10. The term “polyester” is intended to describe anylong-chain polymer having recurring ester groups (—C(O)—O—). Examples ofpolyesters include aromatic polyesters, such as polyethyleneterephthalate (PET), polybutylene terephthalate (PBT), polytrimethyleneterephthalate (PTT), and polytriphenylene terephthalate, and aliphaticpolyesters, such as polylactic acid (PLA). “Polyolefin” includes, forexample, polypropylene, polyethylene, and combinations thereof.“Polyaramid” includes, for example, poly-p-phenyleneteraphthalamid(i.e., Kevlar®), poly-m-phenyleneteraphthalamid (i.e., Nomex®), andcombinations thereof. Natural fibers include, for example, wool, cotton,flax, and blends thereof.

The fabric may be formed from fibers or yarns of any size, includingmicrodenier fibers and yarns (fibers or yarns having less than onedenier per filament). The fibers or yarns may have deniers that rangefrom less than about 1 denier per filament to about 2000 denier perfilament or more preferably, from less than about 1 denier per filamentto about 500 denier per filament, or even more preferably, from lessthan about 1 denier per filament to about 300 denier per filament.

Furthermore, the fabric may be partially or wholly comprised ofmulti-component or bi-component fibers or yarns, which may besplittable, or which have been partially or fully split, along theirlength by chemical or mechanical action. The fabric may be comprised offibers such as staple fiber, filament fiber, spun fiber, or combinationsthereof.

The fabric may be of any variety, including but not limited to, wovenfabric, knitted fabric, nonwoven fabric, or combinations thereof. Thefabric may optionally be colored by a variety of dyeing techniques, suchas high temperature jet dyeing with disperse dyes, vat dyeing, thermosoldyeing, pad dyeing, transfer printing, screen printing, or any othertechnique that is common in the art for comparable textile products. Ifyarns or fibers are treated by the process of the current invention,they may be dyed by suitable methods prior to fabric formation, such as,for instance, by package dyeing or solution dyeing, or after fabricformation as described above, or they may be left undyed.

Other additives may be present on and/or within the target fabric oryarn, including antistatic agents, optical brightening compounds,opacifiers (such as titanium dioxide), nucleating agents, antioxidants,UV stabilizers, fillers, permanent press finishes, softeners,lubricants, curing accelerators, adhesives, and the like. The presentfabrics may also be coated or printed or otherwise aestheticallymodified in addition to being treated with the present antimicrobialcompositions. Printing may be achieved, for example, by screenprintingor flexographic printing techniques.

One specific example of a knit pattern that is suitable for making thefabric that comprises the wound care device of the present invention isa jersey knit. A jersey knit is a circular or flat-knit fabric made witha plain stitch in which the loops intermesh in only one direction. As aresult, the appearance of the face and the back of the jersey fabric iswholly different. Thus, by utilizing a jersey knit to form a fabriccomprised of polyester, nylon, and elastomeric fibers, a fabric may beconstructed that is primarily polyester-containing on one side while theopposite side of the fabric is primarily nylon-containing. Theelastomeric fiber provides some level of stretch to the fabric, whichmay be useful for some wounds that require, for example, a dressing tobe wrapped snugly around the wound site. The elastomeric fiber, inaddition to providing conformability to the wound care device, alsoprovides some level of softness to the device. Spandex is onenon-limiting example of an elastomeric fiber and may be known by thetradename Lycra®, which is available from INVISTA of Wichita, Kans.

Additionally, it may be generally known to those skilled in the art thata knit polyester fabric tends to be hydrophobic, slow to absorb liquids,and generally exhibits little or no wicking of moisture. Since polyesteris hydrophobic in nature, conventional wisdom would lead one to choose ahydrophilic natural fiber, such as cotton, or a hydrophilic syntheticfiber, such as nylon, as the wound contacting side of the wound caredevice. However, it was unexpectedly discovered that by placing ahydrophobic polyester containing surface against the wound site and ahydrophilic nylon containing surface away from the wound site, a uniqueone-way, directional flow of fluid away from the wound site wasachieved.

As noted above, the fluid transport layer 106 comprises a first surface108 and a second surface 110. The first surface 108 of the fluidtransport layer 106 has a first surface energy, and the second surface110 of the fluid transport layer 106 has a second surface energy. In oneembodiment, the surface energy of the second surface 110 of the fluidtransport layer 106 is greater than the surface energy of the firstsurface 108 of the fluid transport layer 106. This difference in surfaceenergies between the two surfaces means that the second surface 110 ofthe fluid transport layer 106 exhibits a greater affinity for aqueousfluids (e.g., perspiration or wound exudates) than the first surface 108of the fluid transport layer 106. Thus, any aqueous fluids absorbed bythe fluid transport layer 106 will be transported or pumped from thefirst surface 108 to the second surface 110 of the fluid transport layer106. This active transportation or pumping of the fluids ensures thatexcess moisture does not accumulate at the interface of fluid transportlayer 106 and a fluid exuding surface, such as the skin or an exudingwound.

When the fluid transport layer comprises first and second surfaceshaving different surface energies, the difference between the twosurface energies can be of any suitable magnitude. In a specificembodiment, the surface energy of the second surface 110 of the fluidtransport layer 106 can be about 101% or more of the surface energy ofthe first surface 108 of the fluid transport layer 106. In more specificembodiments, the surface energy of the second surface 110 can be about102% or more, about 103% or more, or about 104% or more of the surfaceenergy of the first surface 108.

In a specific embodiment, the fluid transport layer 106 can be a textilematerial in which the surface energy of the second surface 110 is higherthan the surface energy of the first surface 108. In order to providethe differential surface energies described above, the fluid transportlayer can also comprise a material in which one surface has beenchemically or physically modified to yield a material having first andsecond surfaces exhibiting different surface energies. For example, inone embodiment, the fluid transport layer can be a textile material suchas those described above having a first surface that has been chemicallytreated in order to lower the surface energy thereof. In such anembodiment, the textile material can be treated, for example, with arelatively hydrophobic fluorocarbon or silicone (i.e., a fluorocarbon orsilicone that is more hydrophobic than the material comprising thenon-treated side of the textile material).

As shown in FIG. 2, such a construction results in a fabric in which thetechnical face of the fabric is predominantly one type of yarn 202, andthe technical back presents a higher proportion of the effect yarn(s)204. Thus, when the yarn 202 and the effect yarn 204 have differentsurface energies or one is more hydrophilic than the other, theresulting fabric will exhibit a different surface energy on each of thetwo major surfaces. In a specific embodiment of the fluid transportlayer depicted in FIG. 2, the yarn(s) 202 are more hydrophilic than theeffect yarn(s) 204. For example, the yarn(s) 202 can be polyamide yarns(e.g., nylon yarns), and the effect yarn(s) 204 can be polyester yarns.Such an embodiment of the fluid transport layer provides a layer inwhich the technical face of the fabric exhibits a higher surface energythan the technical back of the fabric. Thus, when utilized as the fluidtransport layer of the composite article depicted in FIGS. 1A to 1E,such a fabric (i.e., the fabric depicted in FIG. 2) is disposed so thatthe technical back of the fabric forms the first surface 108 of thefluid transport layer 106 and the technical face of the fabric forms thesecond surface 110 of the fluid transport layer 106.

While fiber types are known to be generally hydrophilic or hydrophobicin their natural or initial manufactured condition, this condition canbe changed with chemical and/or physical modification to the fibersand/or textile substrates containing the fibers. For instance, polyesterfiber could be made to exhibit hydrophilic properties via chemicaland/or mechanical treatment. Chemical treatments that may make normallyhydrophobic fibers/fabrics more hydrophilic include, for example, VisaEndurance® fabric treatment available from Milliken & Company ofSpartanburg, S.C. Mechanical treatments that may make normallyhydrophobic fibers/fabrics more hydrophilic include, for example,exposure to mechanical face finishing processes. Exemplary mechanicaltreatments include face finishing treatments like sanding, napping,calendaring, hydroentanglement with gas or liquid, and the like, andcombinations thereof. As a result of these options, in one aspect of theinvention, a suitable fabric may be comprised of treated polyester fiberexhibiting hydrophilic properties and treated polytetrafluoroethylene(“PTFE”) fibers exhibiting hydrophobic properties. In another aspect, asuitable fabric may be comprised of fibers, such as cotton, viscose, orlyocell, with higher hydrophilicity than nylon and treated nylon fibersexhibiting hydrophobic properties.

The layer of perforated silicone gel adhesive is comprised ofpolydimethylsiloxane (also referred to herein as “PDMS” and/or“silicone”) and its derivatives. In one aspect, the perforated siliconegel adhesive is comprised of multiple layers. For example, theperforated trilaminate silicone adhesive layer may be comprised of askin facing silicone layer, a polyurethane layer (e.g. a polyurethanefilm), and an acrylic pressure sensitive adhesive layer. In anotheraspect of the invention, additional adhesive materials may be used inplace of, or in combination with, the silicone gel adhesive. Therefore,the adhesive layer of the present invention may be comprised ofmaterials selected from the group consisting of natural rubber-basedadhesive materials, synthetic rubber-based adhesive materials,hydrocolloid materials, acrylate and/or acrylic materials, polyurethanegel materials, polydimethylsiloxane materials, and the like, andmixtures thereof. In addition, one or more of the following types ofadhesive materials may be suitable for use as the adhesive layer of thewound care device of the present invention:

TABLE A Types of Adhesive Materials Ultraviolet and/or Visible Acrylicsand/or Acrylates Indigo Visible Acrylics and/or Acrylates FlashcureCyanoacrylates Silicones Cyanoacrylates Polyurethane Gel PolyurethaneSynthetic Rubber Surface Insensitive Low Odor and/or Low Bloom Toughenedand/or Flexible General Purpose Primers and/or Accelerators One-PartHeat Cure Epoxies Two-Part Room Temperature Cure Epoxies and/orUrethanes Thermally Conductive Compound Thermally Conductive Gel

Accordingly, any of the foregoing adhesive materials and/or types ofadhesive materials may be used alone, or in combination with oneanother, as the adhesive material comprising the adhesive layer of thewound care device of the present invention. It is also contemplated tobe within the scope of the present invention that at least oneantimicrobial agent may be included in the adhesive material comprisingthe adhesive layer.

The perforations in the adhesive layer may be of any shape and sizesuitable for the end-use application of the wound care device. In oneaspect, a mechanical or electronic rotary die punch machine may be usedto create the perforations in the adhesive layer. The perforations maybe created in the adhesive layer prior to assembling the wound caredevice (e.g. a pre-perforated sheet of silicone), or the perforationsmay be added after at least part of the wound care device has beenassembled. In the latter instance, a needle punching apparatus may beused to needle punch the fluid transport layer through the adhesivelayer. This perforation method may create the apertures in the adhesivelayer and cause the fibers of the fluid transport layer to be pulledthrough the apertures.

The apertures forming the perforations may be of any size. In oneaspect, the apertures in the silicone layer are in the range from about0.1 mm to about 7 mm, or in the range from about 1.0 mm to about 3.0 mm,or even in the range from about 1.3 mm to about 1.9 mm. The aperturesmay be present in the adhesive layer in any pattern. In one aspect, thedistribution of apertures is present in a regular, uniform arrangement.In another aspect, the distribution of apertures may be present in theadhesive layer in a non-uniform arrangement.

In one aspect, the apertures in the adhesive silicone layer may be inthe form of “windows” or openings that are larger in diameter thanconventional apertures or small holes. In this regard, the aperturedadhesive layer may include one window (or opening) or multiple windows(or openings) in the layer. These larger windows or openings may bepresent in a uniform or non-uniform pattern across the surface of theadhesive layer. When one large window is present in the approximatecenter of the apertured adhesive layer, the configuration may bereferred to as a “border” adhesive since adhesive material is presentonly around the outer edges (“border”) of the silicone adhesive layer.One advantage of these window and/or border adhesive layers is that thefluid transport layer, which is present immediately behind the adhesivelayer, will have increased surface contact with the wound site. It isbelieved that having more wound contact may increase the ability of thefluid transport layer to absorb excessive fluid from the wound site andfurther promote wound healing. These window and border adhesive layersare further illustrated one or more of the Figures presented herein.

The percent of perforation (e.g. open space due to apertures or holes oropenings) present in the perforated silicone gel adhesive layer mayvary. In one aspect, the percent of perforation is in the range fromabout 5 percent to about 95 percent, or in the range from about 10percent to about 40 percent, or even in the range from about 11 percentto about 20 percent.

The perforated silicone gel adhesive layer may be of any thickness. Inone aspect, the perforated silicone gel adhesive layer has a thicknessin the range from about 0.05 mm to about 1.0 mm, or in the range fromabout 0.1 mm to about 0.5 mm, or even in the range from about 0.2 mm toabout 0.48 mm.

The adhesive characteristics of the silicone layer are fine-tuned andbalanced to allow a minimum amount of adhesion to the skin and/or woundsite for ease of application of the wound care device, but is containedand capped at a maximum amount of adhesion to prevent disruption ofwound healing upon removal of the device from the wound. Without beingbound by theory, it is believed that silicone is a preferably adhesivedue to its high initial tack which can adhere to the skin for severaldays. However, the adhesive is gentle enough to not damage the wound orperiwound skin upon removal. The adhesive characteristics may bemeasured by ASTM D6862-11, Standard Test Method for 90 Degree PeelResistance of Adhesives. Ideal adhesion of the wound care device on astainless steel substrate may be found in the range from about 0.1 N/25mm to about 4.0 N/25 mm, or in the range from about 0.5 N/25 mm to about2.0 N/25 mm.

Additional layers of material may be included with the wound care deviceof the present invention. For example, a fluid retentive layer may beattached to the fabric layer. The fluid retentive layer may be attachedusing hot melt adhesive. Also, an occlusive (non-perforated) film layermay be attached to the foam layer. The occlusive film layer may beattached using hot melt adhesive. Finally, a release liner may beincluded as part of the packaging of the wound care device. It functionsto protect the silicone gel adhesive prior to use. The release liner isintended to be removed prior to use of the wound care device. Therelease liner may be comprised of material selected from the groupconsisting of polycarbonate, polypropylene, polyethylene, coated paper,and the like, and combinations thereof. The release liner may beprinted.

The fluid retentive layer may be selected from the group consisting offoams, textile materials (e.g. woven, knit, and nonwoven textilematerials), alginates, superabsorbent polymers, gels (e.g., hydrogels),and combinations or mixtures thereof. The fluid retentive layer can alsocomprise a combination of two or more discrete layers, which layers cancomprise any of the absorptive materials listed above. In a specificembodiment, the fluid retentive layer can be a foam, such as an opencell, non-reticulated polymer foam. Such foams can be made from anysuitable material including, but not limited to, polyurethane polymers.In one aspect, a polyurethane polymer used in making such a foam can bea polyester-based polyurethane polymer (i.e., a polyurethane polymermade from a reaction mixture containing a polyester polyol).

The fluid retentive layer of the wound care device may exhibit anysuitable absorptive capacity. For example, the fluid retentive layer mayexhibit a fluid absorption of about 100 wt % or more based on the weightof the fluid retentive layer. In a specific embodiment, the fluidretentive layer may exhibit a fluid absorption of about 200 wt % ormore, about 300 wt % or more, about 400 wt % or more, about 500 wt % ormore, about 600 wt % or more, about 700 wt % or more, about 800 wt % ormore, about 900 wt % or more, or about 1000 wt % or more based on theweight of the fluid retentive layer. The absorptive capacity of thefluid retentive layer may be measured by any suitable means. Forexample, the absorptive capacity of the fluid retentive layer may bemeasured by immersing a known weight of the fluid retentive layer inphosphate-buffered saline containing 0.9 wt % sodium chloride at 37° C.for 30 minutes.

Thus, the wound care device of the present invention is comprised of afabric layer and a perforated silicone gel adhesive layer. The woundcare device may optionally include a release liner that is substantiallycoextensive with the silicone layer. The wound care device may alsooptionally include a fluid retentive layer that is attached to thefabric layer. The fluid retentive layer may or may not be substantiallycoextensive with the fabric layer. Another optional layer comprises anocclusive film layer. In one aspect, the occlusive film layer issubstantially coextensive with the fluid retentive layer. The occlusivefilm layer may be printed with a product logo or other productidentification information.

The wound care device of the present invention may be of any thickness,depending on the construction of the fabric and the thickness of theperforated silicone gel adhesive layer. In one aspect, the thickness ofthe wound care device may be in the range from about 25 to about 60mils, or in the range from about 35 to about 50 mils, or even in therange from about 38 to about 45 mils. It should be understood, and isexemplified herein, that thickness measurements may be increased whenthe wound care device also includes an antimicrobial finish on one ormore surfaces of the wound care device.

An additional advantageous feature of the silver-containing wound caredevice of the present invention is its ability to substantially maintainits original color, despite the presence of effective amounts of asilver-based antimicrobial agent. The elimination of color normallyassociated with the inclusion of silver-based antimicrobials is highlybeneficial and desirable. The wound care devices (preferably,white-colored), as will be described herein, allow users thereof andtheir health care providers to monitor the exudates from the wound.Further, the present wound care devices exhibit long-term colorstability (that is, their color does not change significantly over timewhile in production, transit, or storage). Finally, because the presentwound care device is not discolored by the addition of the silver-basedantimicrobial agent, a variety of substrate colors may be utilized orthe finished wound care devices may be dyed or colored to any desiredshade or hue with any type of colorant, such as, for example, pigments,dyes, tints, and the like. Thus, one or more layers of the wound caredevice may contain a coloring agent. The coloring agent is selected fromthe group consisting of pigments, dyes, tints, and the like, andcombinations thereof.

Antimicrobial and Other Agents

The particular antimicrobial treatment which may be applied to the woundcare device of the present invention comprises at least one silverion-releasing compound selected from the group consisting of silver ionexchange materials (e.g. silver zirconium phosphates, silver calciumphosphates and silver zeolites), silver particles (e.g. silver metal,nanosilver, colloidal silver), silver salts (e.g. AgCl, Ag₂CO₃), silverglass, and mixtures thereof. One preferred silver ion-containingcompound is an antimicrobial silver sodium hydrogen zirconium phosphateavailable from Milliken & Company of Spartanburg, South Carolina, soldunder the tradename AlphaSan®. Other potentially preferredsilver-containing antimicrobials suitable for use herein—includingsilver zeolites, such as a silver ion-loaded zeolite available fromSinanen Co., Ltd. of Tokyo, Japan under the tradename Zeomic®, andsilver glass, such as those available from Ishizuka Glass Co., Ltd. ofJapan under the tradename lonpure®—may be utilized either in additionto, or as a substitute for, the preferred species listed above. Othersilver ion-containing materials may also be used. Various combinationsof these silver-containing materials may be made if adjustments to thesilver release rate over time are desired.

Generally, the silver-based compound is added in an amount from about0.01% to about 60% by total weight of the particular finish composition;more preferably, from about 0.05% to about 40%; and most preferably,from about 0.1% to about 30%. The antimicrobial finish itself, includingany desired binders, wetting agents, odor absorbing agents, levelingagents, adherents, thickeners, and the like, is added to the substratein an amount of at least about 0.01% of the total device weight.

A binder material has been found useful in preventing the antimicrobialfrom flaking onto the wound. Preferably, this component is apolyurethane-based binding agent, although a wide variety of cationic,anionic, and non-ionic binders may also be used, either alone or incombination. Preferably, the binding agent is biocompatible such that isdoes not cause negative reactions in the wound. In essence, such bindersprovide durability by adhering the antimicrobial to the targetsubstrate, such as fibers or fabrics, without negatively affecting therelease of silver ions to the wound.

Total add-on levels of silver to the target substrate may be 20 ppm orhigher. More preferably, total add-on levels of silver may be 200 ppm orhigher. Although an upper boundary limit of silver add-on levels to thetarget substrate has not been determined, consideration of themanufacturing economics and the potential to irritate a sensitive woundsite suggests avoiding excessive silver levels.

Application of Antimicrobial and Other Agents to Substrate

Silver ion-containing compounds (such as AlphaSan®, Zeomic®, orlonpure®) may be admixed in an aqueous dispersion with a binder to forma bath into which the target substrate is immersed. Other similar typesof compounds that provide silver ions may also be utilized.

When specific polyurethane-based binder materials are utilized, theantimicrobial characteristics of the treated substrate are effectivewith regard to the amount of surface available silver that is releasedto kill bacteria, without altering the color of the treated substrate(that is, while substantially maintaining its original appearance).While it currently appears that the use of polyurethane-based binderresins are preferred due to their allowance of silver release andbio-neutral properties, in practice essentially any effective cationic,anionic, or non-ionic binder resin that is not toxic to the wound may beused.

An acceptable method of providing a durable antimicrobial silver-treatedfabric surface is the application of a silver ion-containing compoundand polyurethane-based binder resin from a bath mixture. This mixture ofantimicrobial compound and binder resin may be applied through anytechnique as is known in the art, including spraying, dipping, padding,foaming, printing, and the like. By using one or more of theseapplication techniques, a fabric may be treated with the antimicrobialcompound and binder resin on only one side of the fabric (e.g. the woundcontact surface of a wound care device), or it may be treated on bothsides of the fabric.

The wound care device may then be cut into any geometric shape or sizedepending upon its end-use application. The wound care device may be cutusing a computer controlled cutting device such as a Gerber machine. Itmay also be cut using a mechanical dye cutter, hot knife, straightblade, or rotary blade. The wound care device may be cut into any size,such as, for example, a square, rectangle, triangle, circle and thelike. The length of the wound care device may be 1″, 2″, 3″, 4″, 5″, 6″,7″, and the like and longer. The width may be 1″, 2″, 3″, 4″, 5″, 6″,7″, and the like and longer. The wound care device may be comprised ofany combination of length and width. In one aspect, the wound caredevice may be 2″ by 2″, 2″ by 3″, 3″ by 3″, 4″ by 2″, 4″ by 3″, 4″ by4″, or 4″ by 5″ in size. The wound care device may also be of anyvariety of whimsical shapes, such as, dog bone shape, heart shape,smiley face, or any other shape that is desired. The wound care devicemay also be sterilized prior to use via a variety of heat, chemicaland/or radiation techniques. In one aspect, sterilization may beaccomplished via gamma radiation.

Turning to the Figures, FIGS. 1A and 1B illustrate wound care device 101of the present invention. In consecutive order from wound contactsurface to the surface furthest away from the wound, wound care device101 comprises apertured (or perforated) adhesive layer 102, fluidtransport layer 106 having a wound contact (or wound facing) surface 108and fluid reservoir surface 110, adhesive layer 114, fluid retentivelayer 120, adhesive layer 128, and occlusive film layer 130 having aninner surface 132 and an outer surface 134. Apertured adhesive layer 102contains multiple apertures (e.g. holes or openings) 104.

The fluid transport layer 106 has a first surface 108, which provides afluid-contacting or skin-facing surface for the wound care device 101,and a second surface 110. Adhesive layer 102 is applied to the firstsurface 108 of the fluid transport layer 106. The fluid retentive layer120 has a first surface 122 and second surface 124 and is positioned sothat the first surface 122 is adjacent to the fluid reservoir surface110 of the fluid transport layer 106. Thus, the fluid retentive layer120 can act as a reservoir for the fluids taken up by the fluidtransport layer 106. As depicted in FIGS. 1A and 1B, the fluid transportlayer, fluid retentive layer, and, if present, occlusive film layer maybe attached to each other using adhesive layers 114,128.

FIGS. 1C and 1D illustrate yet another embodiment of the wound caredevice of the present invention. In FIGS. 1C and 1D, wound care device101 is similar to the device of FIGS. 1A and 1B except that wound caredevice 101 has been inverted in order to better illustrate thealternative embodiments of apertured adhesive layer 102. Herein, FIG. 1Ccontains wound care device 101 having, in consecutive order from woundcontact surface to the surface furthest away from the wound, aperturedadhesive layer 102 containing apertures 104, fluid transport layer 106,adhesive layer 114, fluid retentive layer 120, adhesive layer 128, andocclusive film layer 130. The fluid transport layer 106 has a firstsurface 108, which provides a fluid-contacting or skin-facing surfacefor the wound care device 101, and a second surface 110. The fluidretentive layer 120 has a first surface 122 and second surface 124, andocclusive film layer 130 has an inner surface 132 and an outer surface134. FIG. 1C is provided to illustrate that, in one aspect of theinvention, apertures 104 may be of an alternative shape and size thanthat which is illustrated in FIG. 1B. In this instance, apertures 104include four large squares situated in a uniform arrangement across thesurface of apertured adhesive layer 102. Such an arrangement allows forgreater contact between the wound site and fluid transport layer 106.FIG. 1D is the same as FIG. 1C, except that apertured adhesive layer 102is provided as a border (or window) adhesive layer having one largeopening in the approximate center of layer 102. FIG. 1D thus illustratesan exemplary configuration of layer 102 which allows for even greatercontact between the wound site and fluid transport layer 106.

FIG. 1E illustrates yet another embodiment of the wound care deviceaccording to the present invention. FIG. 1E is the same as shown anddescribed for FIG. 1D, except that apertured adhesive layer 102 is shownto be dimensionally larger at its outer edges than all other layers ofwound care device 101. This feature creates an outer adhesive borderaround the remaining layers of the wound care device. While shown to belarger on all four edges in FIG. 1E, it is contemplated to be within thescope of the present invention that apertured layer 102 may bedimensionally larger at its outer edges on one outer edge, on two outeredges, on three outer edges, or on all four outer edges.

As depicted in FIG. 2, fluid transport layer 200 is comprised ofhydrophilic fibers 202 and hydrophobic fibers 204 intermeshed togetherin a jersey knit construction.

FIG. 3A illustrates adhesive layer 102 which is an apertured film havingmultiple discrete apertures (perforations or discontinuities) 104. FIG.3B illustrates yet another embodiment of the invention wherein adhesivelayer 102 is comprised of three layers of material forming a trilaminateadhesive layer. The trilaminate is formed of layers 102 a, 102 b and 102c. In one aspect layer 102 a is comprised of an acrylic material, layer102 b is comprised of a polyurethane film, and 102 c is comprised ofsilicone adhesive.

As can be seen in FIG. 4, perforated adhesive layer 102 comprises aplurality of discrete apertures (perforations or discontinuities) 104.These apertures preferably have a dimension sufficient to permit thepassage of fluid through adhesive layer 102 to the underlying fluidtransport layer formed by the yarn(s) 202 and the effect yarn(s) 204.

FIGS. 5 to 9 are photomicrographs of Example 2, described in greaterdetail later herein. FIG. 5 illustrates multiple apertures present inthe adhesive layer of the wound care device of the present invention.Also, illustrated in FIG. 5 is the fiber of the fluid transport layerpresent in the layer immediately behind/under the adhesive layer. FIG. 5also illustrates one embodiment of the present invention wherein theapertures in the adhesive layer are present in a substantially uniformpattern. FIG. 6 is a view similar to FIG. 5, but at higher magnificationand at a 50 degree angle. FIG. 6 further illustrates the fibersprotruding into the apertures of the wound care device. FIG. 7 shows oneapertures of the wound care device of the present invention at 80×magnification. Polymer stress lines are evident in FIG. 7 and arebelieved to be caused from puncturing the adhesive layer to form theapertures. FIG. 8 illustrates the silver-containing compound present onthe fibers of the fluid transport layer of the wound care device. FIG. 9is a magnified cross-sectional view of some of the layers of the woundcare device. FIG. 9 illustrates, from top to bottom: the release linerfollowed by the silicone adhesive layer followed by the fluid transportlayer followed by the fluid retentive layer (open-cell polyurethanefoam). The lightest colored area along the top surface and the bottomsurface of the fluid transport layer is the silver-containing compound.In this embodiment, the silver-containing compound is present on bothsurfaces of the fluid transport layer. Also illustrated in FIG. 9 is asingle aperture.

FIGS. 10 and 11 are photomicrographs of Comparative Example 1, which isdescribed in more detail further herein. FIG. 10 illustrates themultiple apertures present in the adhesive layer of the wound dressing.However, there is no fiber-containing layer contained within thisdressing as is apparent by looking at the photomicrographs. Rather, anopen-cell foam is present behind/under the adhesive layer. FIG. 10 alsoillustrates the apertures present in Comparative Example 1 in anon-uniform arrangement/pattern. FIG. 11 is a greater magnified view ofthe adhesive layer of Comparative Example 1.

FIGS. 12 and 13 are photomicrographs of Comparative Example 3, which isdescribed in more detail further herein. FIG. 12 illustrates themultiple apertures present in the adhesive layer of the wound dressing.However, there is no fiber-containing layer contained within thisdressing as is apparent by looking at the photomicrographs. Rather, anopen-cell foam is present behind/under the adhesive layer. FIG. 13 is amagnified view of a single aperture present in the adhesive layer ofComparative Example 3.

The following examples further illustrate the present wound care devicehaving fluid transfer properties, but are not to be construed aslimiting the invention as defined in the claims appended hereto. Allparts and percents given in these examples are by weight unlessotherwise indicated.

Sample Creation and Evaluation

A. Substrate Descriptions

The fabric used for Examples 1 and 2 was a jersey knit (circular knit),multi-polymer fabric sold by Milliken & Company. The fabric was singlelayer of fabric comprised of approximately 66% continuous filamentpolyamide yarn, 19% continuous filament polyester yarn, and 15%continuous filament spandex yarn. The polyamide yarn was comprised of 2plies of 40 denier/34 filament count nylon 6 fiber that was exposed to atexturing process prior to knitting. The polyester yarn was comprised ofsingle ply 70 denier/34 filament count fiber that was exposed to atexturing process prior to knitting. The spandex yarn was comprised of55 denier/3 filament count fiber.

The fabric was knitted in such as manner as to give a distinct nylonside and a distinct polyester side. The polyester side of the fabric wasexposed to a face-finishing process known as sanding.

The fabric was passed through a bath containing an antimicrobialformulation (further described below) and subsequently through squeezerollers to achieve a wet pick-up of about 85%. The fabric was then driedin a tenter frame to remove excess liquid.

Silicone Gel Adhesive A was Acrysil™ 150, a trilaminate film comprisedof a layer of silicone adhesive, a polyurethane membrane, and a layer ofacrylic adhesive. Acrysil™ 150 is commercially available from ZodiacCoating of Pusignan, France. The film contained perforations having asize of less than 1.0 mm.

Silicone Gel Adhesive B was Acrysil™ 150, a trilaminate film comprisedof a layer of silicone adhesive, a polyurethane membrane, and a layer ofacrylic adhesive. Acrysil™ 150 is commercially available from ZodiacCoating of Pusignan, France. The film contained perforations having asize of about 1.8 mm.

Silicone Gel Adhesive C-1 was P-Derm® PS-2046, a perforated trilaminatefilm comprised of high adhesion silicone gel skin contact adhesive(1.3N/25 mm), polyurethane, and medical pressure sensitive acrylic. Thisadhesive has a thickness of 0.22 mm and hole size of 1.5 mm with 17%open space. P-Derm® PS-2046 is commercially available from PolymerScience, Inc. of Monticello, Ind.

Silicone Gel Adhesive C-2 was P-Derm® PS-2048, a perforated trilaminatefilm comprised of high initial tack silicone gel skin contact adhesive(1.1N/25 mm), polyurethane, and medical pressure sensitive acrylic. Thisadhesive has a thickness of 0.22 mm and hole size of 1.5 mm with 17%open space. P-Derm® PS-2048 is commercially available from PolymerScience, Inc. of Monticello, Ind.

Silicone Gel Adhesive D was Acrysil™ 150, a trilaminate film comprisedof a layer of silicone adhesive, a polyurethane membrane, and a layer ofacrylic adhesive. Acrysil™ 150 is commercially available from ZodiacCoating of Pusignan, France. Perforations were added to Silicone GelAdhesive D having a size of about 6.0 mm. [we added the perforations,correct?]

Silicone Gel Adhesive E was Acrysil™ 150 with no perforations.

B. Antimicrobial Coating Formulations

Various dispersions of an antimicrobial finish include combinations ofthe following components:

-   -   Antimicrobial AlphaSan® RC2000 silver-based ion exchange        compound, available from Milliken & Company of Spartanburg,        S.C.;    -   Witcobond® W-293 (67% solids) or Witcobond UCX-281F (40%        solids), polyurethane binders available from Chemtura        Corporation of Middlebury, Conn.; and    -   Water.

EXAMPLE 1

Example 1 was comprised of the following sequential layers: Silicone GelAdhesive A, a jersey knit fabric (described previously, available fromMilliken & Company of Spartanburg, S.C.), a hot melt adhesive(copolyamide, PA1008/1-060-014.25 available from SpunFab), apolyurethane foam (Medisponge® 60P available from Essentra), a hot meltadhesive (copolyamide, PA1008/1-060-014.25 available from SpunFab), anda polyurethane film (Inspire® 2340 available from Coveris). The Inspire®film was printed with logo and product identification. No silverantimicrobial was included.

A layer of hot melt adhesive was laid over the top of the jersey knitfabric. The fabric-hot melt composite was then fed into a laminatingmachine, along with all the additional layers in the correctorder/configuration as outlined above. The machine was set at atemperature of 185° C. and a speed of 2.6 m/min. The laminate productwas wound on a take-up roller.

EXAMPLE 2

Example 2 was the same as Example 1, except Silicone Gel Adhesive A wasreplaced with Silicone Gel Adhesive B.

MODIFIED EXAMPLE 2

Modified Example 2 was the same as Example 2, except individual fibersfrom the fluid transport layer were pulled through about 10% of theapertures in the silicone adhesive layer using tweezers.

EXAMPLE 3

Example 3 was the same as Example 1, except Silicone Gel Adhesive A wasreplaced with Silicone Gel Adhesive C-1.

EXAMPLE 4

Example 4 was the same as Example 1, except Silicone Gel Adhesive A wasreplaced with Silicone Gel Adhesive D.

EXAMPLE 5

Example 5 was the Ultra® foam dressing (available from Milliken &Company of Spartanburg, S.C.), which was comprised of a layer ofSilicone Adhesive B (described previously), a layer of jersey knitfabric (described previously), and a layer of polyurethane foam.

C. Comparative Sample Descriptions

Several commercially available wound care devices were also purchasedfor evaluation. They include the following:

COMPARATIVE EXAMPLE 1

“Mepilex® Ag”, a non-adhesive single layer polyurethane foam dressingthat contains silver; available from MöInlycke Health Care AB ofGothenburg, Sweden.

COMPARATIVE EXAMPLE 2

“Mepilex®”, a non-adhesive single layer polyurethane foam dressing;available from MöInlycke Health Care AB of Gothenburg, Sweden.

COMPARATIVE EXAMPLE 3

“Allevyn® Gentle”, a three-layer adhesive dressing comprised of a topfilm layer, a polyurethane foam core middle layer, and an adhesive woundcontact layer; available from Smith & Nephew of London, United Kingdom.

COMPARATIVE EXAMPLE 4

“Allevyn® Ag”, a three-layer adhesive dressing comprised of a top filmlayer, a silver-containing (silver sulfadiazine) polyurethane foam coremiddle layer, and an adhesive wound contact layer; available from Smith& Nephew of London, United Kingdom.

COMPARATIVE EXAMPLE 5

“Optifoam® Ag+”, a non-adhesive dressing comprised of asilver-containing (ionic silver) polyurethane foam layer and a filmlayer; available from Medline Industries, Inc. of Mundelein, Ill.

COMPARATIVE EXAMPLE 6

“Optifoam® Gentle”, a silicone adhesive dressing comprised of a siliconeadhesive layer, a polyurethane foam layer, and a film layer; availablefrom Medline Industries, Inc. of Mundelein, Ill.

COMPARATIVE EXAMPLE 7

“Cutimed® Siltec”, a silicone adhesive dressing comprised of aperforated silicone adhesive layer, a polyurethane foam layer thatcontains superabsorbent particles, and a polyurethane film layer;available from BSN Medical of Hamburg, Germany.

D. Example Testing and Evaluation

Each of the above examples was tested for a variety of characteristicsas will be described below. The silicone adhesive of the inventive woundcare device was the intended wound contact surface. Further,commercially available products (referred to as Comparative Examples 1-7and described above) were also tested for comparison with the inventivewound care device. The test procedures will be described in greaterdetail in the following description. However, a listing of the testsemployed is found below.

-   -   Test 1. Drop Disappearance Test (internally developed method)    -   Test 2. Periwound Protection Test (internally developed method)    -   Test 3. Vertical Leg Model (internally developed method)    -   Test 4. Vertical Wicking    -   Test 5. Peel Strength (ASTM D6862-11)    -   Test 6. Free Swell Bulk Absorption Test (EN 13726-1:2002, Part        1, Test 3.2:Free Swell Absorptive Capacity)

Test 1: Drop Disappearance Test

The purpose of this test is to measure the amount of time it takes for asingle drop of fluid to be absorbed into the substrate. The fluid usedwas simulated wound fluid. Simulated wound fluid is a solution ofdeionized water containing 142 mM of sodium chloride and 2.5 mM ofcalcium chloride. The simulated wound fluid is isotonic to human blood.The simulated wound fluid was contained within a 2 mL syringe. Twomillimeters of fluid were dispensed by hand onto the approximate centerof the substrate. The time it took for the drop to disappear (to beabsorbed into the substrate) was recorded. The test was stopped after600 seconds was reached. Test results are provided in Table 1.

TABLE 1 Drop Disappearance Properties of Inventive and Comparative WoundCare Devices Sample Time (seconds) Example 1 600 Example 2 8 Example 315 Example 4 34 Example 5 5 Comparative Example 1 600 ComparativeExample 2 600 Comparative Example 3 13 Comparative Example 4 n/aComparative Example 5 n/a Comparative Example 6 120

The results shown in Table 1 demonstrate that the inventive wound caredevice having a perforated adhesive film layer (wound contact surface)with apertures of at least 1.8 mm in size demonstrate the fastest dropdisappearance.

Test 2: Periwound Protection Test

The purpose of this test is to measure the amount of moisture or liquidthat is transferred from the dressing to the healthy periwound skin.Simulated wound fluid was used. The apparatus was a syringe pump with1/32″ internal diameter tubing attached to a small hole in the center ofa petri dish. This simulated the wound. A pre-weighed, 2″ diameter pieceof two-layer gauze with a 10 mm hole in the center was placed on thepetri dish with the tubing hole centered within the hole in the gauze.The gauze simulated the periwound skin. A 2″ diameter dressing cutoutwas placed on top of the gauze and a weight of approximately 42 gramswas placed on top of the dressing. Simulated wound fluid was deliveredto the “wound” at a rate of 0.2 mL/hr for 24 hours. At the completion ofthe test, the weight of the gauze was recorded and the percent fluidpick up was determined. Test results are provided in Table 2.

TABLE 2 Periwound Protection of Inventive and Comparative Wound CareDevices Sample Percent Pick Up (%) Example 1 842 +/− 402 Example 2 68+/− 42 Example 3 13 +/− 3  Example 4 40 +/− 51 Example 5 51 +/− 21Comparative Example 1 848 +/− 727 Comparative Example 2 963 +/− 584Comparative Example 3 729 +/− 97  Comparative Example 6 167 +/− 258

The results shown in Table 2 demonstrate that the inventive wound caredevice having a perforated adhesive film layer (wound contact surface)with apertures of at least 1.5 mm in size demonstrated a lower percentpick up and therefore greater periwound protection.

Test 3: Vertical Leg Model Test

The purpose of this test is to measure the amount of fluid that isabsorbed by the wound care device over a period of time in a verticalorientation prior to failure. The fluid used was simulated wound fluid.Failure is defined as the point in time when the wound care deviceeither (a) started to peel from the nylon surface of the leg model orcompletely fell off the leg model, or (b) started to leak simulatedwound fluid from the edges and/or borders of the wound care device.Samples were run at 24 mL/hour until failure. Test results are providedin Table 3.

TABLE 3 Vertical Leg Test Properties of Inventive and Comparative WoundCare Devices Sample Fluid Absorbed (mL) Example 1 47 Example 2 46Example 3 44 Example 4 n/a Comparative Example 1 18 Comparative Example2 n/a Comparative Example 3 19 Comparative Example 4 n/a ComparativeExample 5 n/a Comparative Example 6 43 Comparative Example 7 14

The results shown in Table 3 demonstrate that the inventive wound caredevice having a perforated adhesive film layer (wound contact surface)with apertures of at least 1.5 mm in size demonstrated a significantamount of fluid absorption in a vertical orientation prior to failure.

Test 4: Vertical Wicking Test

The purpose of this test is to measure the amount of fluid that isabsorbed by the wound care device over a certain period of time in avertical orientation. The fluid used was simulated wound fluid. Eachsample was tested in triplicate. The average and standard deviation wascalculated and is presented in Table 4.

TABLE 4 Vertical Wicking Properties of Inventive and Comparative WoundCare Devices Fluid Absorbed (mL) At 10 At 20 At 30 At 40 At 50 At 60Sample seconds seconds seconds seconds seconds seconds Example 1 n/a n/an/a n/a n/a n/a Example 2 2.30 +/− 2.60 +/− 3.12 +/− 3.43 +/− 3.82 +/−4.00 +/− 0.00 0.10 0.16 0.24 0.15 0.00 Example 3 2.27 +/− 3.02 +/− 3.53+/− 3.87 +/− 4.00 +/− 4.00 +/− 0.15 0.14 0.21 0.23 0.00 0.00 Example 4n/a n/a n/a n/a n/a n/a Example 5 2.43 +/− 3.27 +/− 3.83 +/− 4.00 +/−4.00 +/− 4.00 +/− 0.15 0.08 0.06 0.00 0.00 0.00 Comparative 1.40 +/−1.47 +/− 1.47 +/− 1.50 +/− 1.50 +/− 1.53 +/− Example 1 0.10 0.06 0.060.00 0.00 0.06 Comparative 0.97 +/− 1.08 +/− 1.25 +/− 1.37 +/− 1.50 +/−1.60 +/− Example 2 0.21 0.18 0.05 0.08 0.13 0.05 Comparative 1.17+/−1.25 +/− 1.37 +/− 1.43 +/− 1.57 +/− 1.68 +/− Example 3 0.06 0.05 0.060.03 0.08 0.08 Comparative n/a n/a n/a n/a n/a n/a Example 4 Comparativen/a n/a n/a n/a n/a n/a Example 5 Comparative 1.68 +/− 1.93 +/− 2.63 +/−2.90 +/− 3.13 +/− 3.33 +/− Example 6 0.03 0.06 0.03 0.00 0.03 0.03Comparative n/a n/a n/a n/a n/a n/a Example 7

The results shown in Table 4 demonstrate that the inventive wound caredevice having a perforated adhesive film layer (wound contact surface)with apertures of at least 1.5 mm in size demonstrates a significantwicking ability in the vertical direction.

Test 5: Peel Strength Test

The purpose of this test is to measure the amount of force it takes toremove the wound care device from the surface of stainless steel. Eachsample was applied to the surface according to the product directions.Removal of the sample was done by a testing machine with a load weighingsystem. The force required to remove each sample was recorded in gramsof force (gf).

Test results are provided in Table 5.

TABLE 5 Peel Strength of Inventive and Comparative Wound Care DevicesSample Peel Strength (gf) Example 5 193.640 Comparative Example 1 87.662Comparative Example 2 87.361 Comparative Example 3 106.931 ComparativeExample 6 274.968

The results shown in Table 5 demonstrate that the amount of force neededto remove the inventive wound care device from the stainless steelsurface is found in between the amount of force needed for removal ofthe Comparative Examples.

Test 6: Free Swell Bulk Absorption Test

The purpose of this test is to measure the absorptive capacity of adressing. The weight of a 5 cm by 5 cm sample of dressing was recorded.The sample of dressing was added to a dish with a quantity of 37° C.simulated wound fluid that was approximately 40 times the weight of thedressing. The dressing was allowed to sit in the fluid for 30 min at 37°C. At the end of the test the sample was suspended for 30 seconds andweighed. The absorptive capacity of the sample was determined. Eachsample was tested in triplicate. The average and standard deviation wascalculated and is presented in Table 6.

TABLE 6 Free Swell Bulk Absorption Properties of Inventive andComparative Wound Care Devices Sample Absorptive Capacity (g/cm²)Example 1 6341 +/− 47  Example 2 5791 +/− 232 Example 3 6140 +/− 328Example 4 5013 +/− 423 Example 5 5176 +/− 90  Comparative Example 1 7025+/− 465 Comparative Example 2 7837 +/− 463 Comparative Example 3 4690+/− 267 Comparative Example 6 5269 +/− 60  Comparative Example 7 9174+/− 176

The results shown in Table 6 demonstrate that the inventive wound caredevice having a perforated adhesive film layer (wound contact surface)exhibits comparable absorptive capacity to the Comparative Examples.

Test 7: Antimicrobial Efficacy

Antimicrobial efficacy against both Gram-positive (e.g. Staphylococcusaureus ATCC #6538) and Gram-negative (e.g. Klebsiella pneumoniae ATCC#4352) bacteria was measured for inventive and comparative wound caredevices. The quantitative reduction of bacteria after exposure to thesamples versus the control was assessed using a modified version ofAATCC Method 100.

Portions of each wound dressing sample (non-sterile 15 mm diameterdisks) were placed into 24-well microplates. With all samples, thedressings were placed with the side down that normally contacts thewound. Overnight cultures of the test microbes were suspended in 5%nutrient broth in saline ca. 10E6 cells/ml. At time 0, each sample waspre-soaked in sterile saline via immersion. The wells of the 24 wellplate were inoculated with bacteria (0.1 ml of ca. 10E6 cells/nil) andthen the sample was placed contact side down in the inoculum. The 24well plates were then incubated at 37° C. After incubation for 24 hours,the samples were removed and placed into 50 ml centrifuge tubes filledwith 5 ml of a “wash solution” (Tryptic Soy Broth+0.7% Tween 80+0.1%cysteine (to inactivate residual silver)). After vortexing to removeattached cells, the number of viable cells in the solution wasquantified using a microtiter plate-based “Most-Probable Number” assay.The recipe for full-strength Nutrient Broth indicated in this method is5 g/l peptone and 3 g/l beef extract. Duplicate samples were testedagainst Staphylococcus aureus ATCC#6538 and Klebsiella pneumoniae ATCC#4352.

The Control sample was Ultra® foam dressing (available from Milliken &Company of Spartanburg, S.C.) which does not contain a silicone adhesivelayer. The results are shown in Table 7 and FIG. 14.

TABLE 7 Antimicrobial Efficacy Against Gram-Positive and Gram-NegativeBacteria vs. Control Average Log Average Log Reduction vs. ControlReduction vs. Control Against Against Sample ID Klebsiella pneumoniaeStaphylococcus aureus Example 1 3.66 +/− 0.18 2.36 +/− 0.90 (<1.0 mmapertures) Example 2 4.31 +/− 0.59 2.83 +/− 0.67 (1.8 mm apertures)Modified Example 2 3.49 +/− 0.35 2.68 +/− 0.04 (1.8 mm apertures, fiberpull-through) Example 3 3.98 +/− 0.27 2.61 +/− 0.07 (1.5 mm apertures)Comparative Example 1 4.31 +/− 0.59 2.98 +/− 0.45 Control 6.02 +/− 0.184.00 +/− 0.24 (silver, but no silicone)

The results in Table 7 and FIG. 14 indicate that the inventive woundcare devices exhibit antimicrobial efficacy against both Gram-positiveand Gram-negative bacteria. The antimicrobial efficacy is comparable toother commercially available silver-containing wound care devices(Comparative Example 1). Examples 1 to 3 exhibited at least 50% of theantimicrobial efficacy shown by the control sample (no silicone adhesivelayer). In this instance, the data may be interpreted to illustrate thatthe antimicrobial efficacy is reduced by less than 50% when a siliconeadhesive layer is included in the wound care device. Some of Examples 1to 3 exhibited at least 70% of the antimicrobial efficacy shown by thecontrol sample (no silicone adhesive layer). In this instance, the datamay be interpreted to illustrate that the antimicrobial efficacy isreduced by less than 30% when a silicone adhesive layer is included inthe wound care device.

For this testing, Klebsiella pneumoniae was selected as therepresentative Gram-negative microbe and Staphylococcus aureus wasselected as the representative Gram-positive microbe. However, it shouldbe understood to be within the scope of this invention that the woundcare device of the present invention would exhibit similar antimicrobialefficacy against other Gram-positive and Gram-negative bacteria, as wellas against fungi such as C. albicans.

Additional test methods useful for analyzing the wound care device ofthe present invention are as follows:

-   -   Test 8. Fluid Transport Test (Internally developed method)    -   Test 9. Tensile Strength Test (ASTM D 5034)    -   Test 10. Zone of Inhibition Test (Kirby-Bauer Agar Diffusion        Assay)    -   Test 11. Total AlphaSan® RC 2000 Content Test (Ashing Technique)    -   Test 12. Conductivity/Resistivity Test (AATCC Test Method 76)    -   Test 13. Thickness Test (ASTM D 1777-96)

Many of these tests were conducted in commonly owned U.S. Pat. Nos.7,842,306; 8,021,685, and 8,394,403, all of which are incorporated byreference herein.

Test 8: Fluid Transport Test

The purpose of this test is to measure the amount of fluid that istransported from the wound contact side of the wound care device (SideA) to the non-wound contact side of the device (Side B). The test alsoattempts to measure the amount of fluid pushed back to the wound contactside of the device (Side A).

Simulated wound fluid (“SWF”) was prepared by adding 16.60 g NaCl and0.56 g CaCl₂ to a 2 L volumetric flask. The flask was then filled tovolume (2000 mL total) with deionized water. The flask was then cappedand shaken until all of the salts were completely dissolved. Thesimulated wound fluid is comprised of 0.142M (142 mM) NaCl (aq) and0.0025M (2.5 mM) CaCl₂ (aq).

A test sample of a wound care device (5 cm in diameter) was placed ontoa polypropylene disc (5 cm in diameter). Twenty drops of simulated woundfluid was added to Side A of the test sample using a dropper. The testsample was allowed to rest in a horizontal position for 2 minutes. Thetest sample was then sandwiched in a vertical position between two discsof filter paper (Whitman filter paper 3, diameter=110 mm) using aclamp—Filter Paper A contacted Side A of the test sample and FilterPaper B contacted Side B of the test sample. The test sample was held inthis position for 5 seconds. It was determined that the clamp exerts apressure of 340 mm Hg.

Filter papers A and B had been weighed prior to the test. They were thenweighed after the test and difference in weight was determined. Thisweight difference provides a calculation of the amount of SWFtransferred from the wound care device to Filter Paper A and/or B.

The SWF was added to the polyester side (“Side A”) of the wound caredevice of the present invention. SWF was added to the wound contact sideof competitive dressings, as directed by the product brochures.

The values are provided as “percent weight change.” The percent weightchange represents the weight of the fluid absorbed relative to the dryweight of the filter paper. It is calculated by subtracting the weightof the dry filter paper (grams) from the weight of the wet filter paper(grams) and dividing this difference by the weight of the dry filterpaper. This value is then multiplied by 100.

Test 9: Tensile Strength

Tensile strength (grab) of various wound care devices was determinedusing ASTM D 5034. The purpose of this test is to determine structuralintegrity of wet and dry wound care devices. The devices were wetted bydipping them in simulated wound fluid (same formulation as describedpreviously). Measurements are shown in pounds of force (lbf). Highervalues indicate that more force was needed to tear the sample.

Test 10: Zone of Inhibition Test

Zone of Inhibition testing may be conducted to determine theantimicrobial activity of various wound care devices against severalmicrobes using a modified version of the Kirby-Bauer SusceptibilityTest. A brief description of the test method is included below. A fulldescription of the test method may be found in the following document:National Committee for Clinical Laboratory Studies (NCCLS) M2-A8:Performance Standards for Antimicrobial Disk Susceptibility Tests;Approved Standard—Eighth Edition; 2003.

Several Gram-positive and Gram-negative bacteria as well as fungi(yeast) may be chosen to illustrate the antimicrobial efficacy of theinventive wound care device. Gram-positive bacteria include, for exampleand without limitation, Staphylococcus aureus, Clostridium perfringens,Enterococcus faecium and Bacillus cereus. Gram-negative bacteriainclude, for example and without limitation, Klebsiella pneumoniae,Escherichia coli, Acinetobacter baumannii, Enterobacter cloacae, Proteusmirabilis, and Pseudomonas aeruginosa. Fungi, such as yeast, include forexample, Candida albicans and Saccharomyces cerevisiae.

An overnight culture of the test microbe was diluted into saline (0.85%NaCl) to a concentration of 10⁶ cells/ml. Petri dishes containingDiagnostic Sensitivity Test (DST) Agar were inoculated with 0.25 ml ofthe cell suspension and incubated for 1 hour. A sample (15 mm diametercircle) of each wound care device was then placed at the center of theagar plate. The agar plate was incubated for 24 hours at 37° C. Aftermeasuring the extent of the zones (in mm), the samples were transferredto a fresh DST plate inoculated with the same microbe. The process wasrepeated for three days (total).

Test 11: Total AlphaSan® Content

Total ALPHASAN® Content Test

The amount of AlphaSan® antimicrobial incorporated into or onto anarticle can be determined by measurement of elements unique to theantimicrobial compound. For AlphaSan® antimicrobial, the two elements ofhighest abundance are silver or zirconium. Because zirconium is moreabundant in the AlphaSan® antimicrobial product and is easier tomeasure, it is preferable to use zirconium as the signature element fordetermining the level of AlphaSan® antimicrobial in an article. Theamount of AlphaSan® antimicrobial incorporated into or onto the woundcare device was determined using the following ashing technique.

A sample of fabric (weighing approximately 1 gram but with weightmeasured to four significant digits) was placed in a clean, dry ceramiccrucible which had been weighed. The crucible containing the fabricsample was placed in a muffle furnace whose temperature ramped up at 3°C./minute to 750° C. The temperature was then held at 750° C. for fourhours. The system was then cooled and the crucible transferred to adesiccator in which it was allowed to reach an equilibrium temperature.The crucible was then weighed. This provides the percent solids ofinorganic constituents.

The fabric sample was then ground in the ceramic crucible to obtain auniform sample. Approximately 0.05 g weight (again measured to foursignificant digits) was then taken from the ceramic crucible and placedin a platinum crucible. Four milliliters of 50% HNO₃, followed by 15-20drops of 48% HF, were added to the crucible. The crucible was heatedover a hot plate until the sample completely dissolved. The samplesolution was then transferred to a 100 mL volumetric flask.

The crucible was then rinsed with 5% HNO₃, with the rinse solution beingadded to the flask. The solution was diluted to the 100 mL mark with 5%HNO₃. The dilute solution was transferred to a polyethylene storagecontainer. Analysis for the desired active ingredient (in this case,zirconium) was performed using an Inductively Coupled Plasma OpticalEmission Spectrometer device (e.g., a Perkin Elmer Optima 4300DV).Calculations are apparent to one skilled in the art. The amount ofAlphaSan® RC2000 present on the wound care device is provided as aweight percent based on the weight of the fabric.

Test 12: Conductivity/Resistivity Test

The purpose of this test is to determine the conductivity andresistivity (R) of the inventive wound care device. The test wasperformed according to AATCC Test Method 76.

Test 13: Thickness Test

The purpose of this test was to measure the thickness of the inventivewound care device. The test was performed according to ASTM D 1777-96.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the subject matter of this application (especiallyin the context of the following claims) are to be construed to coverboth the singular and the plural, unless otherwise indicated herein orclearly contradicted by context. The terms “comprising,” “having,”“including,” and “containing” are to be construed as open-ended terms(i.e., meaning “including, but not limited to,”) unless otherwise noted.Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate the subject matter of theapplication and does not pose a limitation on the scope of the subjectmatter unless otherwise claimed. No language in the specification shouldbe construed as indicating any non-claimed element as essential to thepractice of the subject matter described herein.

Preferred embodiments of the subject matter of this application aredescribed herein, including the best mode known to the inventors forcarrying out the claimed subject matter. Variations of those preferredembodiments may become apparent to those of ordinary skill in the artupon reading the foregoing description. The inventors expect skilledartisans to employ such variations as appropriate, and the inventorsintend for the subject matter described herein to be practiced otherwisethan as specifically described herein. Accordingly, this disclosureincludes all modifications and equivalents of the subject matter recitedin the claims appended hereto as permitted by applicable law. Moreover,any combination of the above-described elements in all possiblevariations thereof is encompassed by the present disclosure unlessotherwise indicated herein or otherwise clearly contradicted by context.

We claim:
 1. A method for managing moisture at a wound site comprisingthe steps of: (a) providing a wound care device comprising: (i) aperforated trilaminate silicone adhesive layer; (ii) a single layer offabric having a wound contact surface and a wound fluid reservoirsurface; and (iii) a fluid retentive layer; and wherein said wound caredevice transports wound fluid uni-directionally from said wound contactsurface to said wound fluid reservoir surface upon exposure to a wound;(b) placing said wound contact surface of said wound care device incontact with said wound site; and (c) allowing said wound care device totransport wound fluid uni-directionally from said wound contact surfaceto said wound fluid reservoir surface.
 2. The method of claim 1, whereinsaid wound contact surface is coated with a composition comprising atleast one silver ion-containing compound.